High-speed boat



lFeb.11,`1941. 2 @,SARTORL 2,231,296

HIGH-SPEED BOAT Filed Jan. 19, 1'939 Patented Feb. 11, 19.41

UNITED STATES PATENT orticav In Germany January 24, 1938 4o1aims. (c1. 114-665) This invention relates to improvements in the drive or propelling system of high-speed boats and has particular reference to propelling systems for gliding or scooterboats.

It is an object of the invention to provide a propelling system for high speed boats by which the trim of the boat is not changed while at the same time the erliciency is increased compared to the known driving systems. 'i A special object of the invention is to provide a special combination of the propelling or driving means with the `shape of the boat hull, with a view to attaining the above mentioned effects.

With these and other objects in view, as may become apparent from the within disclosures, the invention consistsnot only of the structures herein pointed out and illustrated by the drawing, but includes further structures coming within the scope of what hereinafter may be claimed.

The character of the invention may be best understood by reference to certain ofitsstructural forms, as illustrated Vvby the accompanyingI drawing in whichy Figi is a .side'velevation of a boat speeding thru the water, having the invention applied thereto. l Fig. la is an `enlarged View of the middle portionof Fig. V1.

Fig. 2 is a bottom view of the boat hull.

Fig. 3 is a fragmentary cross sectional view of the boat, on line III--III of Fig. 1, showing especially the outlets for the propellinmg jets.

Referring now to the drawing in greater detail, the boat hull I is provided with a slight keel feature, as shown in Fig. 3. Mounted in the boat hull is a centrifugal pump 2 by which the water is sucked in, thru suction channels 4, and

discharged thru further channels 5 having out--` lets 6 in the form of at nozzles or apertures.

The suction sided water inlets 4 are in the form of longitudinal holes or slots in the bottom surface of the boat hull positioned approximately at the region, with respect to the length of the boat, where the headwave 'I is produced by the boat due to damming up of the water, while the outlets are provided at the front end of a trough 8 provided in the bottom of the boat in front of a step 9 thereof, and extending over the whole width of the hull. The discharged jet of o water flows over the trough 8 and the step 9,

the arrangement being made so that the end portion I0 of the boat again engages the water.

The outlets 6 and the direction of the driving jet discharged therefrom on the one hand and the boat shape on the other hand are arranged and combined in such'a manner that the torsional or twisting moment produced by the driving force of the water jeton the one hand and the resultant force of the boat resistanceon the other hand and tending to change the .trim of 5 the boat is reduced to `a very small amount or even to zero. `The twisting moment disappears if its lever arm becomes zero, i. e. if the driving force acts in a direction which passes thru the centre of `the boat resistance. In an analogous 10 manner the position of the end of the trough 8 upon which the driving jeltximpinges, is advantageouslyvs'o chosen, that the additional buoyancy or lifting force produced by the driving jet at the downwardly inclined end portion of the 15 trough 8 passes through the center ol gravity of the vship displacement,` whereby this moment which also tends to bring the boat out of trim is also eliminated.

For thesale of yclearness the said conditions 20 Y have been indicated diagrammatically in Fig. la, but it will be understood that the forces have been shown purely schematically and that the invention is not limited to the particular relative positions of the forces according to the drawing. The 25 propelling force exerted by the jet of water is indicated by the arrow `I3 and the resultant force" of the boat resistance isindicated by the arrow I4.

- As shown in the drawing, the two forces nearly coincide with each other, with a very small lever 30y arm I6 between the two forces which may even become zero by suitable arrangement of the discharge channel 5. The lifting force exerted by the impinging of the water jet upon the downwardly inclined end portion of the trough 8 is 35 indicated at I] and substantially coincides with the center of gravity of the boat or of the displacement of the boat, respectively, the axis of action of which is indicated by the arrow I8. The lever arm between the forces I'I and I8 o which vis indicated at I9 should be as small as possible or practically zero. f

The operation of my novel arrangement is as follows: The head wave I is reduced by the sucking action of the channels 4 and the bow wave 45 thereby becomes narrower. Also, as a result of the acceleration of the bounding layer by the jet flowing out at 6, the water of the head wave flows more parallelly towards the rear. Furthermore, the jet of water which flows over the trough 8 50 exerts a considerable lifting action upon the rear end of the mould, i. e., the center of the boat. The water surface behind the step 9 no longer takes the course as indicated by the dotted line II, Fig. l, but does take the course accord- 55 .miles per hour) arm on which this force actsand due to the sucing to the full line i2, so that it just reaches the rear end of the boat I0 and supports the same with a minimum friction surface at this end. A further favourable effect is produced since the ship resistance is reduced by the acceleration of the bounding layer of the water and by the fact.

that the resultant of the driving resistance I4 coincides nearly or entirely with the driving force I3. lAs a result of the said favourable effects the Aboat lies almost in a horizontal position in the water and is capable of developing a very high speed.

. It will thus be understood that the jet which is discharged at the front end of the trough and sweeps nearly the whole width of the boat passes at rst over the trough, along the bottom of the ship. It is not necessary for the jet to hug to the arch of the trough, provided only that it impinges upon the downwardly inclined face at the rear end of the trough, whereby an additional dynamic lift is produced and the scooter or gliding boat eiect is increased. This increase is of a particular importance since the velocity of the jet is greaterthan the speed of the 4boat. Also, the boat resistance is decreased in known manner by the. fact that the bounding layer of the water at the boat hull is set to motion.

The superiority ofv my novel reaction drive system for highlspeed boats over screw propeller driver systems resides in the fact that due to the large force of the screw propeller of high speed boats (having, for instance, a speed of more than 20 or even more than 30 nautical together with the large lever tion of the' propeller at the rear end of the boat an undesirable change of trim of the ship is caused so that the Ystem takes up a lower position than the bow while my novel drive does not cause any substantial change of the trim of the boat. As a result of the above mentioned effects, the boat is nearly parallelly lifted .out of the water. l

It is also contemplated to provide the boat with a lat bottom. I prefer, however` to use a boat in the form of a scooter or gliding boat, more particularly a stepped gliding boat.

I claim:

1. A high-speed boat comprising a boat hull which is formed with a transverse trough in its bottom having a downwardly inclined rear end and a water jet propelling system having at least one discharge channel including an outlet aperture for the water jet at the front end of said trough, said aperture being so arranged with respect to said trough that the water jet Y impinges upon the downwardly inclined rear end of the trough.

2. A high-speed boat comprising a beat hull which is formed with a transverse trough in its bottom having a downwardly inclined rear end and a water jet propelling system having at least one discharge channed including an outlet aperture for the water jet at the front end of said trough, said aperture being so arranged with respect to said trough that the water jet impinges upon the downwardly inclined rear end of the trough and said rear end of the trough being so arranged with respect to the center of gravity of the displacement of the boat that the additional lifting force exerted by said water jet upon the trough end substantially coincides with the said center of gravity, whereby the boat when in motion is lifted in a parallel direction.

3. A high-speed gliding boat comprising a stepped boat hull which is formed with a transverse trough in its bottom and a stepped portion behind said trough and a water jet propelling system having at leastone discharge channel including an outlet aperture for the water jet at the front end of said trough, said discharge channel and said trough being so arranged that the propelling water jet engages the boat hull at the rear end of said steppedrportion 4behind said trough. Y

4. A high-speed boat comprising a boat hull which is formed with a transverse trough in its bottom having a downwardly inclined rear end and a stepped portion behind said trough. and a water jet propelling system having at least one discharge channel including an outlet aperture for the water jet in the front end of said trough, said aperture. said-discharge channel and said trough being so arranged that the water jet impinges upon the downwardly inclined rear end of the trough and engages the boei, hull at the rear end of said stepped portion behind said trough.

CHARLES SARTORI. 

